Enhancing the Sustainability of Phosphogypsum Recycling by Integrating Electrodialysis with Bipolar Membranes

Lior Monat, Sanhita Chaudhury, Oded Nir

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Phosphogypsum-a byproduct of phosphoric acid production-piled near eco-sensitive regions, poses both environmental and health risks. By reacting phosphogypsum with NaOH, Ca(OH)2 is produced, which can be utilized for CO2 sequestration. The cost of NaOH, however, and the low market value of the byproduct, a concentrated Na2SO4 stream, hinder the economic viability of this approach. Here, we propose to increase the cost-efficiency of phosphogypsum processing by converting the Na2SO4 to NaOH and H2SO4 using bipolar membrane electrodialysis (BMED). The result is a cleaner and more circular process, as NaOH can be recycled for dissolving phosphogypsum, while H2SO4 can be reintroduced into the industrial phosphoric acid production or used to leach valuable metals out of the phosphogypsum. To assess the feasibility of BMED integration, we used a bench-scale system to probe the trade-off between obtaining high base-product concentration and obtaining high specific energy consumption. This was done for synthetic Na2SO4 solutions at various concentrations, applied voltages, and types of anion-exchange membranes. Economic analysis based on the results showed that a two-step batch BMED process is able to reduce the chemical cost by 50%, as compared to purchasing NaOH. Integrating BMED with existing approaches can, therefore, improve the sustainability and cost-efficiency of phosphogypsum valorization.

Original languageEnglish
Pages (from-to)2490-2497
Number of pages8
JournalACS Sustainable Chemistry and Engineering
Volume8
Issue number6
DOIs
StatePublished - 17 Feb 2020

Keywords

  • CO sequestration
  • Cleaner production
  • Fertilizer industry
  • In-place chemical production
  • Waste valorization

ASJC Scopus subject areas

  • Chemistry (all)
  • Environmental Chemistry
  • Chemical Engineering (all)
  • Renewable Energy, Sustainability and the Environment

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